238 DR. BEALE, ON THE TISSUES. 



generally is sucli that it is impossible to conceive tlie flowing 

 in and out which is imagined. Again, if endosmose continvied 

 for a time, and then the contents remained stationary, and 

 afterwards exosmose occurred, we ought to be able to see the 

 alteration in the size of the cells taking place within a very 

 short period of time ; but no such change has been observed. 

 It is difficult to conceive endosmose and exosmose occurring 

 at the same moment at all parts of the silrface of the cell- 

 wall, for the physical conditions which would lead to the one 

 are absolutely incompatible with the other. Cyclosis in 

 plants has been accounted for by endosmose ; but it would be 

 impossible to cause any particles to pass round and round a 

 closed vesicle in a constant direction by currents flowing in 

 towards the interior from every part of the surface. There 

 are other difficulties in the generally accepted theory which 

 would be tedious to follow out, and as the cell-membrane is 

 not a constant structure, it is unnecessary to show that the 

 changes occurring in the formation of secretions could not be 

 explained by endosmose and exosmose through such a struc- 

 ture, supposing it to exist. 



According to the generally received theory, the cell- wall is 

 considered a most important structure ; but it does not exist 

 constantly. There is a very large class of the lower animals 

 from whose bodies protrusions may be formed in different 

 parts, and these protrusions may meet here and there. AVhere 

 they touch, they coalesce. Clearly, then, there can be no 

 investing membrane here ; neither is a living structure of 

 this kind confined to the lower animals. It exists in man 

 himself. Dr. Beale has seen such protrusions from mucous 

 particles both from the nose and also from the bronchial 

 tubes, under a power of 1700 diameters. A portion of the 

 mass slowly extends itself outwards ; perhaps three or four 

 such outgrowths may be seen in different, parts of the mass. 

 If detached, they assume a spherical form ; but if two come 

 into contact they coalesce. These movements only lasted for a 

 minute, or less, after the mucus was transferred to the glass 

 slide. Protrusions may be often observed to occur from the 

 white blood-corpuscles, and in rare cases the red blood-cor- 

 puscles adhere so intimately to each other that it is difficult 

 not to believe that the outer part of their walls consists of a 

 soft, viscid matter, which runs together when several come 

 into contact.^ 



It is clear, therefore, that the cell-wall is not a constant 

 structure, and that living organisms and elementary parts of 



* A case is mentioned, and a drawing given, at page 264 of the ' Micro- 

 scope in its Application to Clinical Medicine.' (2nd ed.) 



